1. Field of the Invention
This invention relates to a method of controlling hemp sesbania by infection with a fungal pathogen, Colletotrichum truncatum.
2. Description of the Prior Art
Hemp sesbania (Sesbania exaltata) is an economically troublesome weed in soybean production on aluvial clay soils of the lower Mississippi River Valley [McWhorter et al., Weed Science, Vol. 27 (1979), pp. 58-63]. It can cause crop yield reductions by competing for nutrients and water, and by shading the crop plants. It can also reduce crop quality by increasing the amount of foreign material and moisture in harvested beans and by increasing the number of damaged kernels. This weed is also a threat in cotton and rice production.
The procedures for using pathogens to control weeds in annual crops have been described previously for various fungal species. Daniel et al., U.S. Pat. No. 3,849,104, teaches the use of an endemic anthracnose fungus, Colletotrichum gloeosporioides forma specialis aeschynomene, to control the northern jointvetch weed in rice fields. A related species, C. malvarum, has been reported by Templeton in U.S. Pat. No. 3,999,973 as a control for prickly sida (Sida spinosa L.) or teaweed, particularly in soybean and cotton fields. C. malvarum is also pathogenic toward other noncultivated species, including velvetleaf. C. coccodes has been well documented as a widely distributed pathogen of potato and tomato, as well as 35 other plant species throughout the world. One isolate of C. coccodes has been studied as a potential mycoherbicide for velvetleaf by Gotlief et al. [Proceedings, Weed Science Society of America, Vol. 37 (1984), p. 68]. Anderson et al., U.S. Pat. No. 4,715,881, disclose the use of a strain of C. coccodes as a selective pathogen toward eastern black nightshade.
Walker [Weed Science, Vol. 29 (1981), pp. 505-507] discloses the use of Alternaria macrospora as a pathogen against spurred anoda. In Walker, U.S. Pat. No. 4,390,360, A. cassiae is disclosed as an effective biological control agent for sicklepod, showy crotalaria, and coffee senna. Finally, Walker teaches in U.S. Pat. No. 4,419,120 that Fusarium lateritium is useful in controlling prickly sida, velvetleaf, and spurred anoda.